I'll start by noting, I'm still not fully aware of all the "norms"
regarding all that needs to be touched when adding a new file and all
that needs to be done when adding new API's - so I could miss something
that perhaps someone else will pick up on...

hmm... which makes me think, does the description in patch 1/25 need to
be adjusted to indicate that "scsi_host" is expected as part of the
adapter name? and that adapters are thus identified by the numeric
value after the prefix?

No, forcely checking it when parsing is not a good idea, just for
QEMU/KVM driver, we want it has a prefix "scsi_host", it might
be different for other drivers, though currently we only support
qemu driver.
Even checking it here is not that good, but given that this helper
is only used by qemu driver now, I think it's fine, it can be changed
if need in future.

Just checking math and auto decrement order and making sure you get the
result you want. It's the for loop end value decrement inside the loop
which initially got my attention. If "i=1" and "count=2" prior to the
"if", then once we get here the 3rd arg would be 0 (zero), right?
It seems you tried to "steal" what virPCIDeviceListSteal() did, but
avoided or tried to include the virPCIDeviceListFindIndex()
functionality... Perhaps you should make use of the
virSCSIDeviceListFind() just like the PCI code.

As said in commit log, I'm thinking about having a common enough

class for the list, or may be in another way, but it will be later
patch,